Property and Equipment, net - Interest Cost Capitalized and Depreciation and Amortization Expense for Property and Equipment (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest Expense [Line Items]
Interest cost capitalized	$ 5.5	$ 4.2	$ 3.7
Depreciation and amortization expense for property and equipment	$ 170.0	$ 147.2	$ 143.5